China’s COVID-19 situation is on a knife-edge, with a lockdown of its financial hub intensified amid a surge in new cases and reports of new sub-strains of the omicron variant emerging as clusters flare nationwide.

The country, which managed to live much of the pandemic effectively virus free after quashing its initial outbreak in Wuhan, is experiencing its biggest jump in daily infections since that period.

Shanghai reported 9,006 cases Sunday as the city readies to test all 25 million residents in its latest efforts to weed out infections, amid accounts of un-reported deaths in a nursing home and ongoing food shortages. The entire population is now under some form of movement restrictions.